By Nicolle Ritchie and Angie Gradiz
Weather
Storms starting on Sunday, Aug. 9, and continuing into Wednesday brought cumulative precipitation of over an inch in some parts of southwest Michigan. The next week is expected to be warm and mostly sunny, except for storms and showers over the weekend. The forecast for Saturday, Aug. 15, shows significant precipitation, calling for over an inch in some areas.
Crops and pests
Most full-season soybeans are in R5 (seed fill) and will remain in that stage until the seed fills the pod cavity. Symptoms of white mold, sudden death syndrome (SDS) and brown stem rot may start to become visible, although the window for managing them has closed. Watch out for red crown rot, which is a disease not yet confirmed in Michigan that looks similar to SDS and brown stem rot. If you suspect red crown rot, submit a sample to the Michigan State University Plant and Pest Diagnostics Lab. Michigan Soybean Committee and the United Soybean Board will cover the diagnostic fees. You can request soybean sampling kits.
Corn is mainly in kernel development stages. At R2 (blister), the kernels are filled with clear fluid. At R3 (milk), the fluid becomes milky as starches accumulate. R4 (dough) has a pasty consistency, and at R5 (dent), the outside edge of the kernel has an indent. In seed corn, male row destruction continued, and defoliant applications have started to go out.
Tar spot was confirmed in Allegan County this week, according to the Tar Spot Map. Continue to scout for tar spot and evaluate crop risk as kernels develop. Tar spot fungicide applications are most profitable when applied between R1 (silking) and R3 (milky kernel) in corn. According to the Crop Risk Tool, the risk of tar spot development and/or progression was low over the past week.
Source : msu.edu